In order to analyze the heterogeneity of the local behavior of an organic redox flow battery, a dynamic twodimensional model was built at the engineering scale, combining mass and charges transfer, and electrochemical. It is able to simulate correctly the local behavior of a real segmented organic battery and allows to bring additional information about the effect of the internal heterogeneities on the performances. During chargedischarge cycling, the link between the local current density variation and the Faradaic source of charge and reactant depletion was established, and the effect of the concentration distribution during polarization curves was also analyzed. The influence of some parameters of the model shown some unexpected results on the current density profile observed at the negative collector plate. Analysis tools such as the standard deviations of the local current density and of the redox species concentration were developed in order to quantify their internal distribution giving quantitative criteria for redox flow battery performances. Although ignoring transport phenomena at the fiber level, the model reveals the influence of the concentration distribution on the cell behavior and mass-transport limitations at the macroscopic level.